DS-Lite is an IPv4 to IPv6 protocol transition mechanism that is adapted to a broadband service provider infrastructure. DS-Lite provides a bridge between the two protocols and offers an evolutionary path for the Internet to deal with the Internet Address Numbers Authority (IANA) IPv4 address depletion. The IANA IPv4 address depletion is caused by limits in the addressing of IPv4. IPv4 utilizes 32 bit addresses. This limits the total address space to 232 addresses for IPv4. Network address translation (NAT) has been utilized to ameliorate the IANA IPv4 address depletion by the creation of private IPv4 address that are utilized only within specific networks. However, as a result the IPv4 addresses of many end devices are not visible to devices communicating with those devices. Instead an address of the device implementing the NAT is utilized in place of the private IPv4 traffic outside of the network of the device using the private IPv4 address. This introduces a layer of indirection and complexity to the Internet and breaks the original design of direct end to end communication between devices on the Internet.
DS-Lite protocol enables broadband service providers to share IPv4 addresses among customers by combining two well-known technologies: IPv4-in-IPv6 tunneling and NAT. With this combination, DS-Lite enables a transition to the use of IPv6 links between the service provider network and customer premise equipment (CPE). This decouples the deployment of IPv6 in the Internet service provider network (up to the CPE) from the development of IPv6 in the global Internet and in customer applications and devices. Consequently, the IPv4-enabled end user devices are not impacted by the transition from IPv4 to IPv6 by their Internet service provider and can continue using IPv4 addresses, primarily private ones, as is the current situation, allowing for gradual transition to IPv6.
The key elements in DS-Lite technology are an IPv4-in-IPv6 tunnel, which is established between a CPE and the DS-Lite carrier grade Address Family Transition Router Element (AFTR) or large scale NAT (LSN), which plays the role of a central evolved NAT64 node. A key characteristic of the DS-Lite approach is that communications between end-nodes stay within their address family, i.e., IPv6 sources only communicate with IPv6 destinations and IPv4 sources communicate only with IPv4 destinations. There is no protocol family translation involved in a DS-Lite approach.
As the deployment of Ipv6 gains speed and scope, it is expected that many access networks will provide IPv6 connectivity to end-nodes. Such transition will be largely enabled by the deployment of NAT64 technology, which will allow communication between the IPv6-enabled node and an IPv4 destination. However, DS-Lite does not provide end-to-end visibility between IPv6 end user devices and IPv4 end user devices where the IPv4 end user device is assigned a private IPv4 address.